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· Last updated：2026-08-10
This tool is for informational purposes only and does not constitute medical, financial, or legal advice; consult a qualified professional for advice.
Calculate the hourly maintenance fluid rate using the Holliday-Segar 4-2-1 rule: first 10 kg at 4 mL/kg/h, next 10 kg at 2 mL/kg/h, each kg above 20 at 1 mL/kg/h. Also shows the 24-hour total and the 100/50/20 mL/kg/day daily method for cross-checking. Weight in kg or lb (auto-converted). Derived from Holliday-Segar Pediatrics 1957, MDCalc, and Meyers 2009. Not medical advice.
Execution
Fill in the form, run the tool, and review the result in one place.
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Tool usage guide
Calculate an hourly maintenance fluid rate with the Holliday-Segar 4-2-1 rule. Enter weight in kilograms or pounds to see the rate in mL/h, the estimated 24-hour total, and a 100/50/20 mL/kg/day cross-check. This calculator is an estimate, not medical advice.
Background
A clinician needs a quick maintenance fluid estimate for a 70 kg adult.
Problem
The hourly rate must account for the first 10 kg, the next 10 kg, and the remaining weight above 20 kg.
How to use
Enter 70 as the weight, select kg, and leave Decimal Places at 1.
{"weight":70,"weightUnit":"kg","decimalPlaces":1}Outcome
The calculator returns 110 mL/h and 2640 mL/day using the 4-2-1 rule, with a 2500 mL/day 100/50/20 cross-check.
Background
A pediatric patient weighs 12 kg and requires an initial maintenance fluid estimate.
Problem
The team wants to calculate the rate for a weight in the 10–20 kg range.
How to use
Enter 12 as the weight, select kg, and review the calculated hourly and daily values.
{"weight":12,"weightUnit":"kg","decimalPlaces":1}It estimates hourly maintenance fluid: 4 mL/kg/h for the first 10 kg, 2 mL/kg/h for the next 10 kg, and 1 mL/kg/h for each kilogram above 20 kg.
Yes. Select lb as the weight unit, and the calculator converts the value to kilograms before calculating.
It provides the maintenance rate in mL/h, the estimated 24-hour volume, the patient category, and a 100/50/20 mL/kg/day comparison.
No. The 4-2-1 rule is an initial estimate and may require adjustment for clinical conditions such as fever, burns, fluid losses, SIADH, or heart and kidney dysfunction.
No. Use the result as a calculation reference and rely on a qualified healthcare professional for patient-specific decisions.
Outcome
The calculator returns 44 mL/h and 1056 mL/day using the 4-2-1 rule, with a 1100 mL/day 100/50/20 cross-check.
Background
A learner has a patient's weight in pounds but needs a 4-2-1 maintenance rate.
Problem
The calculation requires kilograms, while the available weight uses a different unit.
How to use
Enter the weight and select lb; the calculator converts it to kilograms before applying the rule.
Outcome
The result shows the converted kilogram weight along with the hourly maintenance rate, 24-hour total, and daily-method cross-check.